(a) Field of the Invention
This invention relates to an illuminating optical system for endoscopes wherein a connecting optical system is arranged between a light supplying side light guide and light receiving side light guide.
(b) Description of the Prior Art
In such conventional illuminating optical system for endoscopes of this kind as is mentioned, for example, in Japanese Patent Preliminary Publication No. Sho 55-11216, as shown in FIG. 1, a connecting optical system to be arranged between a light supplying side light guide (light source side light guide) 1 and light receiving side light guide (object side light guide) 2 is formed of a convex lens system 3 and therefore there have been problems that all the peripheral exit light of the exit light out of the exit end face of the light supplying side light guide 1 will be largely bent but all the central exit light will be little bent, therefore, if the light intensity distribution on the exit end face is uneven, the light incident upon the entrance end face of the light receiving side light guide 2 will be uneven in response to the angle, as a result, the exit light of the light receiving side light guide 2 will be also uneven and the light distribution will be uneven within the visual field of the endoscope.